Electric heating unit assemblage



Dec. 6, 1949 K. R. KUENNE ELECTRIC HEATING UNIT ASSEM'BLAGE Filed April 5, 1946 INVENTOR.

KUNO R. KUENNE.

ATTORNEY.

Patented Dec. 6, 1949 ELECTRIC HEATING UNIT ASSEMBLAGE Kuno Robert Kuenne, Oconomowoc, Wis., assignor to A. J. Lindemann & Hoverson Company, Milwaukee, Wis., a corporation of Wisconsin Application April 5, 1946, Serial No. 659,915

8 Claims. 1

This invention relates to insulators for electric wire, cables and the like and more particularly for insulators used to support coiled resistance wires used in the heating elements of electric ovens and broilers. These are commonly called bushings.

One object of the invention is to provide an insulator-support which can be quickly and easily installed in its base plate and by unskilled labor, and which when so installed will be securely and immovably fixed in position and can have the resistance wires mounted therein with equal facility.

Another object is to provide an insulatorsupport or bushing and means for mounting it in the plate which permits various arrangements and enables the maker to obtain the best heat pattern in the oven.

Another object is to provide an insulator-support which is easily replaceable without disconnecting the resistance wire system or disturbing other insulators which jointly aid in supporting an electric heating element.

Another object is to provide an insulatorsupport which when in place acts in the dual capacity of a heating element support and as a corrosion protector for the metal plate on which it is mounted, there being relatively few exposed edges of the plate as potential corrosion starting points.

Another object is an insulator-support which provides a more even distribution of resistance wire tension and which will continue to support a heating element even though some of the tension is relaxed due to breakage of a coacting insulator-support or a resistance wire or damage to the latter, or otherwise.

Another object is to reduce to a minimum the number of parts required to make a complete heating element assembly, thereby simplifying and strengthening the structure and reducing the chances of failure of competent parts.

Other objects and advantages of this invention will be obvious from the following description and the accompanying drawings.

Referring to the drawings:

Fig. l is a side view of an insulator-support, with resistance wire therein in position on a base plate constituting an exemplary embodiment of the invention;

Fig. 2 is a plan view of the insulator-support attached to a base plate;

Fig. 3 is a plan view of electric heatin units, base plates and insulator-supports on a reduced scale, embodying the invention, the top plate 1.

being broken away to expose the bottom structure.

Referring to the drawings, I is a top base plate such as is employed for a broiler while I I, H are open bottom frames constituting base metal plates disposed edgewise vertically of an oven or other heating compartment. 2 is the base of the insulator-support or holder which has substantially rectangular recess 3 cut in it at the tap of its base on one side and a rounded shoulder or step 4 located at its opposite side. Preferably the recess 3 and shoulder 4 are made of a width only slightly greater than the thickness of the base plate I and are on the same level, so that the outer side of the base plate and the end edges of its oblong opening 9 are engaged by them. The outer or heating element holding portion of the insulator-holder is in the form of a hook 5 of considerable thickness whose bottom at 8 is made of a size to accommodate the diameter of the helical wire heating element 8 while the distance between the terminal end H] of the hook and its shank 1 is slightly less than the diameter of the spiral resistance element used. Thus in assembly the said element is snapped or forced into the supporting loop or section 6 through the said channel, 1, which tapers inwardly. In the drawings, as shown in Fig. 2, the preferred form of base plate I is provided with rectangular openings 9 whose length is approximately the distance between the bottom of recess 3 and the shoulder 4 and whose width is the Width of the insulatorsupport.

The openings 9 and the insulating holders positioned therein are of any desired number and are arranged in any desired positions, though preferably in staggered relation, to give any suitable heat pattern, but be arranged so that the tension of the resistance wire causes pressure against the bottom 6 of the hook or loop. They are also I so located that the holding insulators depend downwardly from the upper plate l and extend inwardly from the frames H and I2 and are drawn toward that position by the tens-ion. If a bottom horizontal plate is employed, the back of the loop 6 may be extended so that the said holders cannot gravitate down through the opening if the tension is rdeased. This extension should be located just above recess 4.

In practice the arrangement of the heating element is decided upon and exact sized rectangular orifices cut at critical extremes, as shown in Fig. 3. The oven or other heater is then assembled and the plates with insulatorsupports thereon placed in position therein.

By reason of the peculiar construction of the insulator-supports it isnecessary to tilt them so that the stepped portion carrying the step enters the orifice first, at such an angle that when the hook terminus Iii approaches or touches the plate I, as shown in dotted lines in Fig. l, the insulator-support may be swung so that the plate I may be received by the recess 3. Only after the plate l is within the recess 3 may the insulator be turned back so that the bottom 4 of the step or shoulder 4 rests against the V loops is always sufficient to hold them in place.

After the insulating supports or *holdersare in Should the said wire become broken from.

become stretched or broken, and the maintenanceof the holder .in .properposition in the metal plateby the tension of theresistance wire, so that contact between the said wire and the plate cannot occur.

Certain features relating to the construction *hereinzshownand described are described and ing the holders, which willremain in position claimed in. my copending application filed August 2,1949, Serial N 0. 108,219.

What. I claim is: 1. In a device of the character described, a base plate having a series of openings therein,

removable insulating holders for resistance wires position the heating element 8 is snappedlintoplace and connected to suitable outlets, as indicated at.l3 and Id. This. is done under proper tension.

It will be seen from the foregoing, that no lock or other connecting means between the insulatorholders and the at the edge of each holder isgripped .by the recess 4%, and cannot be released except by a turningand then a sliding movement of the holder. the turning movement being necessary to re move the opposite edge of the aperture from abutment with the shoulder; that a simple die construction only is required to make the elongated apertures; that lacing the coiled resistance wire is reduced'to a very simple operation quickly and easily performed;.and that.replacing the resistance wires and insulatorholders is likewise asimple andeasy operation which can be performed astoone or more without disturbing the others. .Itwill also be seen that no twisting or turning of 'theresistance wires or holders .is necessary to :connect and secure these parts, and that no movements of the holder after it is engaged by the wire is necessary. Nor is anyrotary movement of the insulator-holders necessary to mount it in its plate or release it therefrom. 'Otheradvantages of the improvements will be 'apparent'to those familiar With the devices of this character and their manufacture and use. Various changes in the details of construction of the exemplary embodiment of the improvements herein shown and described may be made, such as may be necessary to improve its functions or adapt it to other or'more extended uses, without departing from the scope of the invention. Thus the frame and insulator-holders at bottom may be omitted and a heating unit of the calrod type substitutedyand the form of the resistance wires may be varied according to the best pr. ctices of the art and the judgment of the manufacturer. The form of the hook-shaped holder may also be varied to coact with different forms of resistance wire or for other purposes. It is important to the invention, however, that the insulatoreholder shall-in normaluse be held in proper position in the backing plate or frame and the parts besecured in ;their correct operativepositions and relations by the tension of the resistance wire. V V One 'of the specific features 'of the improvements is .found in the form 'of loop section '6, which is preferably made of strong porcelain-and has substantially rectangular edges, which engage the convolutions of the resistance wire passing therethrough under tension and extending away from the holder on both sides at an angle thereto. This ensures positive engagement between the interior of the hook or loop and the resistance wire and prevents the latter at all times-from slipping, therethrough, even should it plate is required, since the plate positioned in said openings substantially filling said openings and rotatable on an axis parallel to .the plane .of the said base plate, resistance wires extending through saidholders and under lengthwise tension, said holders'having wire receiving recesses therein .ofa size to receive and engagesaid .Wires .and also having recesses .on their opposite sides spaced from said wire receiving recesses of .asizeto receive andreceiving and ..en a ins said'plateat the edges of said openings, there beinga portion of each of said holders. oppositesaid plate-receiving recess-extending .beyondthe edge .of the plate opening on theside of the plate awayjfrom the Wire receiving portion of 'thehol'der and lapping the plate when the other .edge .of the opening is} in the saidrecess, the tensionof said wire when disposed at an angle to the longitudinal axis of the holder being such as to constantly pressthe inner wall of said plate receiving recessagainst the edge of the plate therein,

2. In ,a device of the character described, a base platehavinga series of rectangular oblong openings =therein, removable insulating holders for resistance wires positioned in said openings substantially filling said openings. and rotatable onanaxisparallel tothe'plane ofthe said base plate,- resistance wiresextending through said holders. and under lengthwise tension, said holders having wire receivingrecesses therein of a size .to receivesand. engage .said wires .and also I having recesses on their opposite sides spaced from said wire receiving recesses of ,a size to receive and receivingand engaging said plate at the edges of saidopeningsjthere being a portion of each of said holders oppositesaid plate-receiving recess extending beyond the edge of the plate opening on the side of-the plate away from the wire receiving portion ofthe'holder and lapping the plate when the other edge, of the opening is in the said recess, the tension of said wire when disposed at anangle to the longitudinal axis of the.holder being such as toconstantly press the innerwall of said plate. receiving recess against theedge of itheplate therein. 7

'3. In a ,device of the .character described, a base plate having .a,,.series,..of openings therein, in staggered relation,.removable insulating holders .for resistance wirespositioned in said openings;substantiallyfilling said openings and rotatable .onan, axis parallelto the planecfthe said base plate, resistance wires extending through said holders and underlengthwise tension, said holders having wire receivingrecessestherein of a. sizeto receive and engage. .said wires and also. havingrecesses ontheir opposite sides spaced from said wire receiving recesses of a. size to receiveandreceiving and engaging saidplate at the edges ofsaidopenings, therebeinga portion of .eachof said holders, opposite said plate-er ceiving recess ,extendingbeyond the edge .of. the plate. opening onrtheside of theplate away from the wire receiving portion of the holder and lapping the plate when the edge of the opening is in the said recess, the tension of said wirewhen disposed at an angle to the longitudinal axis of the holder being such as to constantly press 1e inner wall of said plate receiving recess against the edge of the plate therein.

4. In a device or the character described, a base plate having a series of openings therein, removable insuiating holders for helical resistance wires positioned in openings substantially filling said openings and rotatable on an axis parallel to the plane of the said base plate, resistance wires extending through said holders and under lengthwise tension, said holders having wire receiving recesses therein of a size to receive and engage said wires and also having recesses on their opposite sides spaced from said wire receiving recesses of a size to receive and receiving and engaging said piate at the edges of said openings, there bein a portion of each of said holders opposite said plate-receiving recess extending beyond the edge of the plate opening on the side of the plate away from the wire receiving portion of the holder and lapping the plate when the other edge of the opening is in the said recess, the tension of said wire when disposed at an angle to the longitudinal axis of the holder being such as to constantly press the inner wall of said plate receiving recess against the edge of the plate therein.

5. In a device of the character described, a base plate having a series of substantially rectangular openings therein, removable insulating holders for resistance wires positioned in said openings substantially filling said openings and rotatable on an axis parallel to the plane of the said base plate, resistance wires extending through said holders and under lengthwise tension, said holders having wire receiving recesses therein of a size to receive and engage said wires and also having recesses on their opposite sides spaced from said wire receiving recesses of a size to receive and receiving and engaging said plate at the edges of said openings, there being a portion of each of said holders opposite said platereceiving recess extending beyond the edge of the plate opening on the side of the plate away from the wire receiving portion of the holder and lapping the plate when the other edge of the opening is in the said recess, the tension of said wire when disposed at an angle to the 1ongitudinal axis of the holder being such as to constantly press the inner wall of said plate receiving recess against the edge of the plate therein.

6. In a device of the character described, a base plate having a series of openings therein, removable insulating holders for resistance wires positioned in said openings substantially filling said openings and rotatable on an axis parallel to the plane of the said base plate, resistance wires extending through said holders and under lengthwise tension, said holders having open wire receiving recesses therein of a size to receive and engage said wires and also having recesses on their opposite sides spaced from said wire receiving recesses of a size to receive and receiving and engaging said plate at the edges of said openings, there being a portion of each of said holders opposite said plate-receiving recess extending beyond the edge of the plate opening on the side of the plate away from the wire receiving portion of the holder and lapping the plate When the other edge of the opening is in the said recess, the tension of said wire when disposed at an angle to the longitudinal axis of the holder being such as to constantly press the inner wall of said plate receiving recess against the edge of the plate therein.

7. In a device of the character described, a base plate having a series of openings therein, removable insulating holders for resistance wires positioned in said openings substantially filling said openings and rotatable on an parallel to the plane of the said base plate, resistance wires extending through said holders and under lengthwise tension, said holders having wire receiving recesses therein of a size to receive and engage said wires and also having recesses on their opposite sides spaced from said wire receiving recesses of a size to receive and receiving and engaging said plate at the edges of said openings, there being a portion of each of said holders opposite said plate-receiving recess extending beyond the edge of the plate opening on the side of the plate away from the wire receiving portion of the holder and lapping the plate when the other edge of the opening is in the said recess and a shoulder adjacent thereto en aging an edge of the plate opening spaced from the said plate receiving recess a distance approxtmately equal to the greatest diameter of the plate opening and blocking movement of said holder in a plane parallel to the plate the tension of said wire when disposed at an angle to the longitudinal axis of the holder being such as to constantly press the inner wall of said plate receiving recess against the edge of the plate therein.

8. In a device of the character described, a base plate having a series of openings therein, removable insulating holders for resistance wires positioned in said openings substantially filling said openings and rotatable on an axis parallel to the plane of the said base plate, resistance wires extending through said holders and under lengthwise tension, said holders having wire receiving recesses therein of a size to receive and engage said wires and also having recesses on their opposite sides spaced from said wire receiving recesses of a size to receive and receiving and engaging said plate at the edges of said openings, there being a portion of each of said holders opposite said plate-receiving recess extending beyond the edge of the plate opening on the side of the plate away from the wire receiving portion of the holder and lapping the plate when the other edge of the opening is in the said recess, the tension of said wire when disposed at an angle to the longitudinal axis of the holder being such as to constantly press the inner wall of said plate receiving recess against the edge of the plate therein and to press the said plate lapping portion of the holder against the surface of the plate.

KUNO ROBERT KUENNE.

REFERENCES CITED The following references are of record in the file of this patent:

UNITED STATES PATENTS 

